Research On The Development Of Short-Air-Gap Corona Discharge And Characteristics Of Ion Wind Field Based On Schlieren Technique

Ion wind is a unique phenomenon in the process of corona discharge,also known as corona wind.Ion-wind devices have a broad application prospect in the fields of heat dissipation,drying,dust removal and microelectronic devices.In recent years,the main research contents in this field include the study of electrode structure,such as using metal net electrode and filamentous metal electrode as the electrode,and some scholars also prepare nanomaterials as the electrode.Researchers also pay attention to the influence factors of ion wind performance,such as electrode structure and humidity,on ion wind output.In addition,there are more and more researches on the mechanism of ion wind,and the performance of ion wind is optimized in the process of continuous exploration.In this paper,the optical,electrical and flow field characteristics of ion wind under short air gap were studied by using cone-sphere,needle-sphere and multi-needle-net electrode structures.The effects of electrode structure,gap distance,voltage amplitude and voltage polarity on ion wind characteristics were mainly studied.A photoelectric-joint monitoring system was built by using photomultiplier,Rogowski coil,schlieren and ICCD camera.According to the flow field characteristics and photoelectric properties of ion wind under the cone-sphere and needle-sphere electrode,it can be found that only within a certain range voltage amplitude,can ion wind used for industrial production be produced;and under the same voltage amplitude,the ion wind speed under the needle-sphere electrode is larger than that under the cone-sphere electrode,with smaller corona noise and larger emission angle.The most important is that under the needle-sphere electrode,the ion wind with the same speed can be generated under the lower voltage amplitude,which means that having the needle-sphere electrode as ion wind generator can save power,improve the energy transfer efficiency.This indicates that the curvature radius of the electrode is the key factor influencing the ion wind velocity,and the parameters of the ion wind generator such as electrode structure,voltage amplitude and electrode spacing still need to be optimized continuously.In this paper,a multi-needle-net electrode structure is designed.It is found that there exists an optimal side length under certain conditions,and too large or too small mesh side length can inhibit the development of ion wind.Increasing the number of needle electrodes can effectively increase the ion wind speed.Optimization of the needle electrode arrangement can also greatly improve the ion wind speed: the more uniform the needle electrode arrangement,the greater the ion wind speed.In a certain voltage range,the higher the voltage amplitude,the more conducive to the formation of ion wind,so the ion wind speed will increase with the increase in voltage amplitude,but at the same time the case that corona noise is too large need to be eliminated.In the COMSOL Multiphysics simulation software,the coupling method of electrostatic field module and dilute material transfer module was used for modeling,and the distribution law of ion density in ion wind and the shape characteristics of ion wind under positive polarity DC voltage were calculated,which was in good agreement with the experimental results.This proves that the generation of ion wind under positive polarity DC voltage is caused by the movement of neutral molecules driven by positive ions under the electric field,and also indicates that the plasma composition in ion wind is less,which is essentially a weakly coupled motion of dispersed charges.The work done in this paper has reference value for establishing more perfect industrial application of ion wind.